Golf practice mat with virtual divot feature

ABSTRACT

An artificial turf for golf mimics visual and physical aspects of natural turf. The artificial turf includes a resilient, slow recovery, foam layer that temporarily deforms proximate to where the club head contacts the artificial turf during a swing, thereby allowing an uninterrupted swing arc with a descending angle of attack and forming a virtual divot cavity that mimics physical aspects of a natural turf divot. Trans-chromic synthetic grass blades on the surface of the artificial turf exhibit a temporary color change caused by contact with the club head during a swing, thereby forming a virtual divot cavity that mimics visual aspects of a natural turf divot. The slow recovery foam and trans-chromic grass blades enable analysis of the golf swing based on the virtual divot. The artificial turf may be incorporated into a practice mat.

TECHNICAL FIELD

The subject matter of the present disclosure is generally related toartificial turf and golf practice mats.

BACKGROUND

Many sports are played on natural turf. Natural turf includes soil andnatural grass that requires frequent maintenance. Artificial turf isalso used as a playing surface in some sports. Artificial turf hassynthetic fibers that mimic the appearance of natural grass. Artificialturf is more durable than natural turf and does not require sunlight,irrigation, or trimming. Consequently, artificial turf is often favoredfor covered stadiums and other indoor venues. However, artificial turfdoes not provide the same feel as natural turf as a playing surface.

The game of golf is typically played outdoors on natural turf. However,artificial turf practice mats are often used for golf practice ranges,indoor golf simulators, and other situations in which natural turf wouldbe subject to excessive wear, be difficult to grow, or would otherwisebe impractical. Although a wide variety of artificial turfs are known,existing artificial turf golf practice mats do not accurately mimic allthe characteristics of natural turf that are significant to the sport ofgolf.

SUMMARY

All examples, aspects and features mentioned in this document can becombined in any technically possible way.

In accordance with an aspect an apparatus comprises: an artificial turfcomprising a trans-chromic material. In some implementations thetrans-chromic material is part of synthetic blades of grass. In someimplementations, the trans-chromic material is a thermochromic material.In some implementations the artificial turf comprises a resilientcompressible layer. In some implementations the thermochromic materialexhibits a base thermochromic coloration at 20 to 25 degrees Celsius. Insome implementations the base thermochromic coloration is green. In someimplementations the thermochromic material exhibits an activatedthermochromic coloration, different than the base thermochromiccoloration, above 25 degrees Celsius. In some implementations theactivated thermochromic coloration is tan, brown, or red. In someimplementations the synthetic blades of grass comprise a thermochromicadditive that is introduced to a base material. In some implementationsthe base material comprises at least one of nylon, polyethylene,ethylene-vinyl acetate, and poly ethylene-vinyl acetate. In someimplementations the thermochromic additive comprises at least one ofspirolactones, fluorans, spiropyrans, fulgides, bisphenol A, parabens,1,2,3-triazole derivates, and 4-hydroxycoumarin. In some implementationsthe trans-chromic material comprises polymeric imitation opals. In someimplementations the resilient compressible layer comprises viscoelasticfoam. In some implementations the resilient compressible layer comprisespolyurethane foam. In some implementations the resilient compressiblelayer has a thickness of from 2 to 4 cm. In some implementations theresilient compressible layer has a recovery time from a compressed stateto a decompressed state of from 5 to 20 seconds.

In accordance with an aspect an apparatus comprises: a golf practice matcomprising: a stance mat; and an artificial turf located in an openingin the stance mat, the artificial turf comprising synthetic blades ofgrass comprising a trans-chromic material. In some implementations theartificial turf comprises a resilient compressible layer. In someimplementations the trans-chromic material is a thermochromic materialwhich exhibits a base thermochromic coloration at 20 to 25 degreesCelsius and exhibits an activated thermochromic coloration, differentthan the base thermochromic coloration, above 25 degrees Celsius. Insome implementations the resilient compressible layer comprisesviscoelastic foam or polyurethane foam.

In accordance with an aspect an apparatus comprises: an artificial turfcomprising: synthetic blades of grass comprising a thermochromicmaterial that exhibits a base thermochromic coloration at 20 to 25degrees Celsius and exhibits an activated thermochromic coloration,different than the base thermochromic coloration, above 25 degreesCelsius; and a resilient compressible layer comprising at least one ofviscoelastic foam and polyurethane foam.

BRIEF DESCRIPTION OF THE FIGURES

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 illustrates a proper golf swing.

FIG. 2 illustrates ascending and descending angles of attack.

FIG. 3 is a profile view of artificial turf with natural turf-likecharacteristics.

FIGS. 4 and 5 illustrate a proper swing and virtual divot with theartificial turf of FIG. 3.

FIGS. 6A, 6B, and 6C illustrate analysis of a golf swing with theartificial turf.

FIG. 7 illustrates a golf practice mat that incorporates the artificialturf.

DETAILED DESCRIPTION

U.S. Provisional Patent Application 62/650,319, titled GOLF PRACTICE MATWITH VIRTUAL DIVOT FEATURE, and filed on Mar. 30, 2018, is incorporatedby reference.

To understand the characteristics of turf that are significant in thesport of golf it is helpful to understand aspects of a proper golfswing. Referring to FIGS. 1 and 2, the game of golf involves striking agolf ball 100 with a golf club to launch the golf ball toward a hole.The golf club includes a shaft 102 with a grip at one end and a clubhead 104 at the other end. The golfer holds the grip and swings the clubto strike the golf ball 100 with the club head 104. The swing startswith a backswing in which the club head moves in an arc away from thegolf ball, and then changes to a fore-swing direction in which the clubhead moves in an arc toward the ball. After striking the golf ball thegolfer continues to swing the club in a follow-through motion until theswing is completed. A swing in which the club head travels in anuninterrupted arc 106 with a descending angle of attack 202 relative tothe golf ball is generally considered good technique. An aspect of sucha swing is that the club head 104 contacts the golf ball 100 beforetraversing a low point 108 of the uninterrupted swing arc 106. Ideally,a central portion of the face of the club head 104, commonly referred toas the “sweet spot,” is where the club contacts the golf ball 100.Contact with the sweet spot with a descending angle of attack 202 in anuninterrupted arc 106 most efficiently launches the golf ball withdesired speed, loft, backspin, and distance. It should therefore beunderstood that characteristics of turf that enable such a swing aresignificant in the sport of golf.

A well-known result of a good golf swing on natural turf is creation ofa divot. When the sweet spot of an iron-type golf club is properlyaligned with a golf ball resting on the surface of the turf in anuninterrupted swing arc 106 with a descending angle of attack 202, theclub head contacts the turf 110 shortly after contacting the golf ball100. More specifically, the lower portion of the club head 104,including the leading edge and sole, traverses the turf 110 down to andthrough the low point 108. Traversal of natural turf by the club headresults in a portion of natural turf known as a “divot” being partiallyor completely cut away from the adjacent soil. A shallow depression iscreated where the divot is cut away from the adjacent soil. The shallowdepression may also be referred to as a divot. The divot indicates wherethe leading edge of the club made contact with the natural turf relativeto the location of the golf ball, the plane of the swing arc, thedirection of travel of the club head upon impact with the natural turf,where was the golf ball struck relative to the ideal horizontal andvertical sweet spot locations on the club head face, and how far anddeep the club head travelled through the natural turf and thus theelevation of the swing arc, among other things that enable analysis ofthe swing. It should therefore be understood that characteristics ofturf that enable formation of divots are significant in the sport ofgolf.

One of the shortcomings of existing artificial turf and golf practicemats is that a swing characterized by a descending angle of attack 202in an uninterrupted arc 106 is inhibited. If the golfer attempts anuninterrupted swing arc 106 with a descending angle of attack 202 thenthe club head is sharply deflected by unyielding artificial turf,thereby interrupting the swing arc. Consequently, the golfer is forcedto use an altered swing arc 204 to reduce the force of impact with theartificial turf. The altered arc 204 results in an ascending angle ofattack 200 upon contact with the golf ball. The ascending angle ofattack 200 typically results in a poor-quality golf shot. Consequently,existing artificial turf may reinforce improper swing technique.

Another shortcoming of existing artificial turf and golf practice matsis that a swing does not result in generation of a divot. As mentionedabove, divots enable analysis of the golf swing. Existing artificialturf and golf practice mats typically do not generate a divot or providea visual indication of the characteristics of the swing. Some practicemats may have surface materials that are reoriented by contact with theclub head to provide some visual evidence, but those materials do notautomatically recover a pre-swing orientation or create a divot.

FIGS. 3 through 5 illustrate an artificial turf 300 that enables aproper golf swing and generation of a virtual divot 302. The artificialturf may be implemented as a composite of multiple layers that mimicdifferent aspects of natural turf. A first layer 304 may consist of orinclude synthetic grass blades 306 that form a top or outer surface ofthe artificial turf 300 and mimic visual aspects of natural turf. Thesynthetic grass blades may be oriented at pseudorandom angles and have avariety of lengths to mimic the appearance of real blades of grass. Thesynthetic grass blades 306 are affixed to a second layer 308 thatprovides a flexible backing surface and anchors the grass blades. Afirst distal end 310 of each synthetic grass blade is attached to thesecond layer 308 and a second distal end 312 extends away from thesecond layer. In addition to anchoring the synthetic grass blades thesecond layer 308 protects a third layer 314 from the club head. Thethird layer has properties that allow deformation to mimic physicalaspects of natural turf. A fourth layer 316 provides a substrate towhich the third layer 314 is affixed. The fourth layer may havecharacteristics and properties that help to secure the artificial turfin place on an underlying surface. Aspects of individual layers aredescribed in greater detail below.

The first layer 304, and specifically the synthetic grass blades 306,mimic the visual appearance of natural turf and natural turf divots viaselective coloration and color variation. These trans-chromic aspectsmay be accomplished via use of thermochromic materials. Thermochromismis a material property in which coloration of a material is dependent onthe temperature of the material. The synthetic grass blades may have aselected base thermochromic coloration, e.g. green, at typical ambienttemperatures such as 20 to 25 degrees Celsius, and a different activatedcoloration at slightly higher temperatures. Club head swings rangingfrom 100-160 kph may impart enough frictional energy to the syntheticgrass blades to raise the surface temperature of the synthetic grassblades by 5 to 15 degrees Celsius. The thermochromic material may beselected such that the increase in temperature caused by friction from agolf swing results in a thermochromic change in coloration from the basecoloration to the activated coloration. For example, the grass bladesmay change from the green base coloration to a tan, brown, or redactivated coloration in response to a golf swing. As the grass bladescool back to ambient temperature the coloration returns to the basecoloration. When implemented for a wider range of ambient temperatures,such as for outdoor use, the base coloration and activated colorationmay vary as a function of the ambient temperature. In other words, thecolor would change although not necessarily from a single basecoloration to a single activated coloration.

In some implementations a thermochromic additive is introduced to a basematerial to create synthetic grass blades that change color in responseto the frictional energy associated with a golf swing. The base materialmay include nylon, polyethylene, ethylene-vinyl acetate, polyethylene-vinyl acetate, or other suitable materials. The base materialmay include or be treated with UV inhibitors to protect against colorfade and material breakdown from prolonged exposure to sunlight. Thethermochromic additive may include a thermochromic liquid crystal orleuco dye such as spirolactones, fluorans, spiropyrans, fulgides,bisphenol A, parabens, 1,2,3-triazole derivates, and 4-hydroxycoumarin.The thermochromic additive may be microencapsulated. Inmicroencapsulation, small particles or droplets of the thermochromicmaterial are surrounded by a coating of a different material to createsmall capsules. The size of the microcapsules may range between 3-5 μm.Pigments may be mixed with the thermochromic microcapsules. In someimplementations a thermochromic dye or paint is applied to the exteriorsurface of the base material. The thermochromic properties may beselected such that the synthetic grass blades temporarily change from abase color, for example green, to a highlight color, for example tan orbrown, in response to contact with the golf club during a swing. For astructured color variant, the change may be a spectral shift such asgreen to blue and back again. The synthetic grass blades may revert tothe pre-contact base color in 5 to 30 seconds as the surface of thesynthetic grass blades returns to ambient temperature.

Another trans-chromic method of achieving the desired color change forthe synthetic grass blades is using polymeric imitation opals. Naturalopals are made up of evaporatively formed silica spheres that reflectand diffract light to form a variety of colors. A polymer opal iscomprised of hard nanoparticle spheres distributed in a flexible outershell that will similarly diffract light and generate a structuralcolor. The size of the nanoparticle and the spacing between them willdetermine which wavelengths of light will be visible. The nanoparticlesare crosslinked polystyrene and the outer layers are a soft polyethyleneacrylate. The nanoparticles can be produced to a common size to controltheir visible structural color. When this synthetic grass material isdeformed—stretched or compressed—the spacing of the particles changesand with it, so does the structural color. When the material elasticallyreforms to its original shape, the original color returns as well. Asthere are no pigments involved, the color properties will not fade overtime.

The second (backing/interface) layer 308 may be manufactured frommaterials including, but not limited to, polypropylene, syntheticrubber, or elastomers such as EPDM (ethylene propylene diene monomer(M-class)) rubber with a thickness of 0.3 to 1.5 mm. The second layermay exhibit cut-resistance properties that help to maintain theintegrity and durability of the artificial turf. The second layer mayalso be pliable and readily deform in response to the force appliedthrough contact with the club head during a swing. In someimplementations continuous filaments of spunbonded polypropylene areformed into a web that is heat bonded at filament crossover points. Theresult is a loose web that does not provide significant resistance tothe club head during a swing. The synthetic grass blades may be attachedto the second layer through a tufting or weaving process. The secondlayer also provides an interface between the first and third layers.

The third layer 314 may be manufactured from resilient deformablematerials including, but not limited to, foam. Examples include LRPu(low-resilience polyurethane) foam and viscoelastic foams such as“Confor foam” or “memory foam.” viscoelastic foams such as Confor foamand memory foam include polyurethane and other materials that increaseviscosity and density. Thickness of the third layer may be 2 to 4 cm,for example, and without limitation. Compression of the third layerproximate to contact with the club head 104 and resulting from the forceapplied by the club head creates a shallow depression, i.e. a virtualdivot 302, that mimics the physical appearance of a divot formed innatural turf. Depth of the virtual divot varies but will typically befrom 0.5 to 1.25 cm. The polyurethane foam may be selected such thatrecovery time from a compressed state to a decompressed state is about 5to 20 seconds. Consequently, the virtual divot persists for an amount oftime that enables analysis of the swing. The third layer may be attachedto the second weave layer only along the perimeter.

The fourth layer 316 may be manufactured from a hard rubber or othermaterial. The fourth layer may have anti-skid properties that resistsliding when horizontal forces are exerted upon it. The fourth layer maybe rigid or flexible. The fourth layer may be glued or otherwise affixedto third layer. In some implementations the fourth layer isspray-applied to the third layer. The fourth layer may be bonded to thethird layer at the entire contact surface.

One of the advantageous characteristics of the artificial turf 300 isdeformability. Because the third layer is deformable the artificial turfexhibits an amount of resistance to a golf swing that is like naturalturf. Deformability helps to enable an uninterrupted swing arc with adescending angle of attack like natural turf. Consequently, proper swingtechnique can be practiced and reinforced on the artificial turf.

Another advantageous characteristic of the artificial turf isresiliency. After being deformed by contact with a club head theresilient artificial turf returns to its pre-contact shape and volume,thereby automatically resetting for another swing. Another aspect ofresiliency is reversible color variation. Specifically, the syntheticgrass blades in the virtual divot formed by compression of the foamlayer temporarily change color to mimic the exposed soil of a naturalturf divot and then return to the pre-contact color over time. Forexample, the virtual divot may automatically revert from tan to green inabout the same amount of time required for the foam layer to decompressback into its pre-contact shape and volume. The recovery period may bean amount of time that allows visual evaluation of the virtual divotwithout hindering a succession of swings at a frequency that is commonfor a practice shot session or virtual golf game. Consistent swingcharacteristics of any quality of successive swings may increase therecovery time of the shape and color of the artificial turf, therebyproviding additional information about the golfer's swing. Consequently,the artificial turf may be suitable for use with golf simulators andpractice ranges that require golf balls to be hit from the same locationin succession.

Referring to FIGS. 6A, 6B, and 6C, another advantageous characteristicof the artificial turf 300 is that the virtual divot facilitatesanalysis of the golf swing. Because the virtual divot has the shape andappearance of a natural turf divot, the virtual divot may visuallyindicate characteristics of the swing such as where the leading edge ofthe club made contact with the artificial turf relative to the locationof the golf ball, the plane of the swing arc, the direction of travel ofthe club head upon impact with the artificial turf, where was the golfball struck relative to the ideal horizontal and vertical sweet spotlocations on the club head face, and how far and deep the club headtravelled through the artificial turf and thus the elevation of theswing arc, among other things. In FIG. 6A artificial turf 300 includes aball placement mark 602 on which the golf ball is placed. Virtual divot604 indicates that the club head contacted the artificial turf atlocation 606 before contacting the golf ball and the left-right (L-R)direction of the swing was properly aligned. The virtual divot 608 shownin FIG. 6B indicates that the club head contacted the artificial turf atlocation 610 before contacting the golf ball and the left-rightdirection of the swing was improperly aligned (moving from right toleft). The virtual divot 612 shown in FIG. 6C indicates that the clubhead contacted the artificial turf at location 614 before contacting thegolf ball and the left-right direction of the swing was properly alignedbut the club head face was open (or closed, depending on whether thegolfer is left-handed or right-handed), resulting in alteration of theleft-right direction/plane of swing.

FIG. 7 illustrates a practice mat 700 made with the artificial turfdescribed above. The practice mat includes a small section 702 of theartificial turf, which may include markings as described above. Thefourth layer material of the small section may be wrapped around theedges, e.g. attached to the edges of the second and third layers. Thesmall section 702 is inserted into an opening in a larger stance golfmat 704. The larger stance golf mat may have different properties thanthe artificial turf, e.g. different firmness and density, to support thegolfer. The size of the mat may be selected for portability or to fitinto an opening in a floor or other surface. Together, the small section702 of artificial turf and stance golf mat 704 may provide a realisticexperience like golfing on natural turf.

Several features, aspects, embodiments and implementations have beendescribed. Nevertheless, it will be understood that a wide variety ofmodifications and combinations may be made without departing from thescope of the inventive concepts described herein. Accordingly, thosemodifications and combinations are within the scope of the followingclaims.

1. An apparatus comprising: an artificial turf comprising: syntheticblades of grass comprising a trans-chromic material that changes from afirst color to a second color in response to contact with a golf clubduring a golf swing, the synthetic blades of grass returning to thefirst color in from 5 to 20 seconds following changing to the secondcolor in response to the golf swing; and a resilient compressible layerthat compresses from a first shape into a second shape in response tocontact with the golf club during the golf swing, the resilientcompressible layer returning to the first shape in from 5 to 20 secondsfollowing being compressed into the second shape in response to the golfswing; whereby a virtual divot that exhibits changed coloration andshape suitable for analysis of the golf swing exists for from 5 to 20seconds following the golf swing.
 2. The apparatus of claim 1 whereinthe trans-chromic material is incorporated into the synthetic blades ofgrass.
 3. The apparatus of claim 2 wherein the resilient compressiblelayer comprises memory foam.
 4. The apparatus of claim 1 wherein thetrans-chromic material is a thermochromic material that exhibits a basethermochromic coloration at 20 to 25 degrees Celsius.
 5. The apparatusof claim 4 wherein the base thermochromic coloration is green.
 6. Theapparatus of claim 4 wherein the thermochromic material exhibits anactivated thermochromic coloration, different than the basethermochromic coloration, above 25 degrees Celsius.
 7. The apparatus ofclaim 6 wherein the activated thermochromic coloration is tan, brown, orred.
 8. The apparatus of claim 1 wherein the synthetic blades of grasscomprise a thermochromic additive that is introduced to a base material.9. The apparatus of claim 8 wherein the base material comprises at leastone of nylon, polyethylene, ethylene-vinyl acetate, and polyethylene-vinyl acetate.
 10. The apparatus of claim 9 wherein thethermochromic additive comprises at least one of spirolactones,fluorans, spiropyrans, fulgides, bisphenol A, parabens, 1,2,3-triazolederivates, and 4-hydroxycoumarin.
 11. The apparatus of claim 1 whereinthe trans-chromic material comprises polymeric imitation opals.
 12. Theapparatus of claim 1 wherein the resilient compressible layer comprisesviscoelastic foam.
 13. The apparatus of claim 1 wherein the resilientcompressible layer comprises polyurethane foam.
 14. The apparatus ofclaim 1 wherein the resilient compressible layer has a thickness of from2 to 4 cm.
 15. The apparatus of claim 3 wherein the first color is greenand the second color is brown.
 16. An apparatus comprising: a golfpractice mat comprising: a stance mat; and an artificial turf located inan opening in the stance mat, the artificial turf comprising: syntheticblades of grass comprising a trans-chromic material that temporarilychanges from a first color to a second color in response to contact witha golf club during a golf swing, the synthetic blades of grass returningto the first color in from 5 to 20 seconds following changing to thesecond color in response to the golf swing; and a resilient compressiblelayer that compresses from a first shape into a second shape in responseto contact with the golf club during the golf swing, the resilientcompressible layer returning to the first shape in from 5 to 20 secondsfollowing being compressed into the second shape in response to the golfswing; whereby a virtual divot that exhibits changed coloration andshape suitable for analysis of the golf swing exists for from 5 to 20seconds following the golf swing.
 17. The apparatus of claim 16 whereinthe resilient compressible layer comprises memory foam.
 18. Theapparatus of claim 16 wherein the thermochromic material exhibits a basethermochromic coloration at 20 to 25 degrees Celsius and exhibits anactivated thermochromic coloration, different than the basethermochromic coloration, above 25 degrees Celsius.
 19. The apparatus ofclaim 18 wherein the resilient compressible layer comprises viscoelasticfoam or polyurethane foam.
 20. An apparatus comprising: an artificialturf comprising: synthetic blades of grass comprising a thermochromicmaterial that exhibits a base thermochromic coloration at 20 to 25degrees Celsius and exhibits an activated thermochromic coloration,different than the base thermochromic coloration, above 25 degreesCelsius; and a resilient compressible layer comprising at least one ofviscoelastic foam and polyurethane foam that compresses from a firstshape into a second shape in response to contact with a golf club duringa golf swing, the resilient compressible layer having a recovery time offrom 5 to 20 seconds.